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Polymerization‐induced phase separation takes place when a miscible component of the monomer becomes immiscible as the polymer is formed. One example is the polymerization of methyl methacrylate (MMA) in the presence of poly(ethylene glycol) (PEG). Depending on the initial conditions, microscopic structures, including porous structures, co‐continuous monolith structures, and particle aggregation structures, are obtained. In this study, the phase separation process is analyzed using an optical microscope and fluorescence microscope. The nucleation or spinodal decomposition in the initial stage, subsequent growth in the microscopic domains, and eventual fixation of the structure are observed. The observed images are analyzed using image analysis software. The particle number and the particle size as a function of reaction time are evaluated. Conversion and molecular weight distribution as a function of reaction time are also analyzed. [ABSTRACT FROM AUTHOR]

Bulk polymerization directly provides glassy polymers from liquid monomers and has been used for many engineering applications. Recently, it has drawn attention for potential use as a resin for fiber‐reinforced plastics and additive manufacturing. For such applications, detailed and precise information of the reaction kinetics, including non‐ideal conditions, is required. Here, we investigate the reaction kinetics of isothermal bulk polymerization using differential scanning calorimetry (DSC) at a broad temperature ranged from 40°C to 90°C. 2,2'‐Azobis(isobutyronitrile) (AIBN) or 2,2'‐Azobis(4‐methoxy‐2,4‐dimethylvaleronitrile) (V‐70) is used as an initiator. We analyze the data focusing on the onset of sudden reaction acceleration known as Trommsdorff effect. Because of the reaction kinetics and the nature of Trommsdorff effect, a higher temperature does not always lead to a shorter time for the completion of the reaction. We discuss the reaction kinetics in conjunction with the molecular weight distributions. [ABSTRACT FROM AUTHOR]

Reversible addition–fragmentation chain transfer (RAFT) polymerization of 2‐(tert‐butoxycarbonyloxy)ethyl methacrylate (BHEMA) is carried out using 4‐cyano‐4‐((dodecylsulfanylthiocarbonyl)sulfanyl)pentanoic acid as the RAFT agent. The polymers with a controlled molecular weight and polydispersity are produced when a large amount of the RAFT agent is used. The RAFT polymerization of isobutyl methacrylate is also carried out using poly(2‐(tert‐butoxycarbonyloxy)ethyl methacrylate) (PBHEMA) as the macro‐RAFT agent in order to synthesize diblock copolymers with a narrow molecular weight distribution. It is revealed that the control of the polymerization of BHEMA is achieved under limited polymerization conditions. Then, the acid‐catalyzed deprotection of tert‐butoxycarbonyloxy groups of PBHEMA is performed in the presence of trifluoroacetic acid at room temperature to obtain polymers with a hydroxy group in the side chain. The hydroxy‐containing polymers are further reacted with 2‐isocyanatoethyl acrylate and methacrylate to synthesize precursor polymers used for a thermally curing system. [ABSTRACT FROM AUTHOR]

Colloidal crystals with non‐close‐packed structures, such as body‐centered cubic (bcc) structures, are of high interest. Nanosized protrusions, prepared from colloidal crystals, are interesting for biomimetic applications. Herein, self‐assembly approaches for synthesizing colloidal crystals with square lattice nanoprotrusions are presented. In the first approach, spin‐coating and subsequent heating of colloidal silica and acrylic monomer results in a bcc‐like arrangement; the number of stacked colloid layers and the colloid density of these compounds are important in the formation of this structure. Moreover, prolonged heating exposes colloids from acrylic monomer, with square lattice nanoprotrusions formed. In the second approach, the protrusions are fabricated in a shorter time by replacing some of the acrylic monomer with volatile media. Only certain volatile media, such as a solvent with a structure similar to diethylene glycol, exhibit the formation of square lattice protrusions. These bottom‐up approaches contribute toward high‐throughput techniques for fabricating metastable square lattice colloidal arrangements. [ABSTRACT FROM AUTHOR]

Recently the β relaxation draws attention because it may act as a precursor of the α relaxation and potentially influences a wide range of properties. In many cases, the weak intensity of the β relaxation limits the experimental investigation. Herein, the β relaxation of poly(diethyl fumarate) (PDEF) using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and dielectric spectroscopy is investigated. Originating from the absence of methylene spacer in the main chain, polyfumarates possess an intense β relaxation. Unlike common vinyl polymers, PDEF shows two distinct steps in DSC measurement corresponding to α and β relaxations. Interestingly, the relative intensities of α and β relaxations depend on the thermal history. The β relaxation of PDEF obtained by dielectric spectroscopy at high temperature is similar to that of poly(methyl methacrylate) (PMMA). However, the β relaxation of PDEF follows the VFT equation rather than the Arrhenius equation at low temperatures. The analysis of PDEF/PMMA blend suggests the local orientation of PDEF chain plays a vital role in the intense β relaxation. [ABSTRACT FROM AUTHOR]

Hydrogels were prepared by electron beam (EB) radiation to the aqueous solutions of poly(sodium acrylate) in the presence of potassium and ammonium peroxodisulfates. The effects of EB radiation dose, as well as polymer, and initiator concentrations on the formation of gels, were investigated. On the basis of the storage modulus, loss modulus, and complex viscosity of the isolated gels determined by rheological measurement, the relationship between the radiation conditions and the rheological properties of the gels was discussed. Furthermore, hydrogels with a gradient crosslinking structure in a depth direction were synthesized by controlling EB radiation dose. [ABSTRACT FROM AUTHOR]

Double‐network hydrogels were conveniently synthesized by the one‐shot radical polymerization of an ionic monomer for the first network and a non‐ionic monomer for the second network in the presence of crosslinkers by simultaneous addition of the monomers, that is, one‐shot and spontaneous two‐step polymerization accompanying the delay of polymerization of a second network monomer. We analyzed the polymerization process based on the conversion of each monomer during the reaction in the absence of crosslinkers. Then we fabricated the double‐network hydrogels using several polymerization systems consisting of a conjugated monomer and a non‐conjugated monomer in the presence of the dual crosslinkers. We analyzed the swelling, mechanical and viscoelastic properties of hydrogels synthesized by one‐shot radical polymerization to confirm the production mechanism and the network structure of the hydrogels. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

UV absorption spectroscopic measurements and DFT calculations revealed that N‐(alkyl‐substituted phenyl)maleimides with substituents at the ortho position favored a twisted N‐phenyl conformation, due to the steric hindrance between the maleimide ring and the substituted N‐phenyl moiety. High‐molecular‐weight copolymers were synthesized by radical copolymerization of the N‐(alkyl‐substituted phenyl)maleimides with n‐butyl vinyl ether and n‐butyl acrylate. The thermal properties of the copolymers were determined by thermogravimetric analysis and differential scanning calorimetry. The mechanical tensile tests under temperature control revealed the mechanical features of the copolymers depending on their repeating structure and composition. The significant temperature dependence of the modulus and strain of the copolymers was also clarified. Then, the transparency, refractive indices, and birefringence properties of the copolymer films were evaluated. It was confirmed that the maleimide copolymers had negative orientational birefringence with small absolute values and positive photoelastic birefringence. The effect of the conformational structure of the N‐phenyl groups on the thermal, mechanical, and optical properties of the copolymers was discussed. [ABSTRACT FROM AUTHOR]

Optical tissue clearing methods are attractive for three‐dimensional imaging of intact tissues and organs. A CLARITY (clear lipid‐exchanged acrylamide‐hybridized rigid imaging/immunostaining/in situ‐hybridization‐compatible tissue‐hydrogel) method using polyacrylamide gels was recently developed. In the current study, we used poly(acrylamide‐co‐styrenesulfonate) gels as a polyelectrolyte gel for a passive CLARITY method. First, radical copolymerization of acrylamide (AAm) and sodium p‐styrenesulfonate (SS) at different ratios was performed. The composition of the copolymer could be controlled by changing the monomer ratio. With increased SS content, the molecular weight decreased and the refractive index slightly increased. The poly(AAm‐co‐SS) hydrogels with a higher SS content were more swollen and looser. The clearing time could be reduced using the poly(AAm‐co‐SS) hydrogel with a higher SS content. Three‐dimensional fluorescence imaging of the poly(AAm‐co‐SS) hydrogel‐cleared tissues was successfully performed after treatment using a blue fluorescent DNA stain. Therefore, the use of the poly(AAm‐co‐SS) hydrogel improved the clearing process in the passive CLARITY method, and the technique is useful for fluorescence imaging of DNA. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2297–2304, 2019. [ABSTRACT FROM AUTHOR]

N‐substituted maleimides polymerize in the presence of a radical initiator to give polymers with excellent thermal stabilities and transparency. In this study, we synthesized various maleimide copolymers with styrenes and acrylic monomers to control their thermal and mechanical properties by the introduction of bulky substituents and intermolecular hydrogen bonding. Three‐component copolymers of N‐(2‐ethylhexyl)maleimide in combination with styrene, α‐methylstyrene (MSt), or 1‐methylenebenzocyclopentane (BC5) as the styrene derivatives, and n‐butyl acrylate, 2‐hydroxyethyl acrylate, 4‐hydroxybutyl acrylate, or acrylic acid as the acrylic monomers were prepared by radical copolymerization. These copolymers were revealed to exhibit excellent heat resistance by thermogravimetric analysis. Glass transition temperatures increased by the introduction of bulky MSt and BC5 repeating units. The mechanical properties of the copolymer films were improved by the introduction of intermolecular hydrogen bonding. Optical properties, such as transmittance, refractive index, Abbe number, and birefringence, were determined for the copolymers. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1569–1579 [ABSTRACT FROM AUTHOR]

The reversible addition‐fragmentation chain transfer polymerization of diisopropyl fumarate (DiPF) was carried out using ethyl 2‐[[(dodecylthio)thioxymethyl]thio]‐2‐methylpropionate (T1) and 1,1′‐(1,2‐ethanediyl) bis[2‐[[(dodecylthio)thioxymethyl]thio]‐2‐methylpropionate] (T2) as the monofunctional and difunctional chain transfer agents (CTAs) to synthesize poly(diisopropyl fumarate) (PDiPF) with a rigid chain conformation. The obtained PDiPF had a well‐controlled molecular weight, molecular weight distribution, and structure of the chain ends. Size exclusion chromatography and NMR measurements revealed an excellent introduction efficiency (84–98%) of the terminal trithiocarbonate group into the polymer chain end. They were available as the monofunctional and difunctional macro‐CTAs to synthesize the AB and ABA block copolymers, respectively. While the well‐controlled block copolymers were solely obtained by the polymerization of 2‐ethylhexyl acrylate as the second monomer in the presence of PDiPF as the macro‐CTA, the block copolymerization of DiPF using poly(2‐ethylhexyl acrylate) as the macro‐CTA failed. The trithiocarbonate group at the chain end was completely removed by the reaction with n‐butylamine and it was valid for the improvement of the coloration and other optical properties of the transparent polymers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2584–2594 The reversible addition‐fragmentation chain transfer (RAFT) polymerization of diisopropyl fumarate was carried out using mono‐ and difunctional chain transfer agents (T1 and T2) to synthesize poly(diisopropyl fumarate) (PDiPF) with a well‐defined molecular weight, molecular weight distribution, and structure of the chain ends. They were available for the synthesis of the AB and ABA block copolymers with poly(2‐ethylhexyl acrylate) (P2EHA). The trithiocarbonate group at the chain end was removable by reduction to provide highly transparent polymers. [ABSTRACT FROM AUTHOR]

A thermally stable and transparent copolymer (PAED) composed of N‐allylmaleimide, N‐(2‐ethylhexyl)maleimide, and diisobutylene as the repeating units was produced by radical copolymerization in the presence of an azo initiator in chloroform at 60 °C. The thiol–ene reaction between the allyl groups included in the side chain of PAED and the mercapto groups (SH) included in a random‐type SH‐modified silsesquioxane (SQ) as the crosslinker provided PAED–SQ hybrid materials upon heating. The reaction process for this thermal curing was monitored from the intensity changes of characteristic peaks by IR spectroscopy as well as the gravimetric determination of the isolated insoluble fractions. The thermal, optical, and mechanical properties of the hybrids were investigated. The onset and maximum decomposition temperatures were 322–369 °C and 399–431 °C, respectively. The weight residue at 800 °C was 16–40 wt%, which depended on the amount of the SQ content in the feed. These organic–inorganic hybrid materials were highly transparent and exhibited refractive index of 1.522–1.524 and Abbe number of 40.0–45.8. The tensile test and dynamic mechanical analyses were also carried out to investigate the mechanical properties and the network structures of the hybrids. The addition of triallylisocyanurate (TAIC) to the curing system efficiently improved the conversion of the allyl and SH, leading to the more dense network structure and the higher strength and hardness of the cured hybrids. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2294–2302 Organic–inorganic nanohybrid materials were synthesized by the thiol–ene reaction of an N‐allylmaleimide copolymer (PAED) and a random‐type SH‐modified silsesquioxane (SQ) as the crosslinker. The cured hybrid materials were confirmed to be transparent and exhibited excellent thermal stability. The addition of triallylisocyanurate (TAIC) to the curing system efficiently improved the conversion of the allyl and mercapto groups, leading to the more dense network structure and the higher strength and hardness of the cured hybrids. [ABSTRACT FROM AUTHOR]

ABSTRACT: Various types of polymers containing tert‐butoxycarbonyl (BOC) moiety as the typical protecting group of functional moieties have been used for the design of stimuli‐responsive polymer materials. In this study, we investigated the heat‐responsive deprotection behavior of BOC‐containing polymers obtained by radical polymerization of 4‐(tert‐butoxycarbonyloxy)styrene (BSt) and copolymerizations of BSt with styrene and methyl acrylate. The deprotection of BOC groups accompanying the evolution of isobutene and carbon dioxide as gaseous products was monitored by thermogravimetric analyses at different temperature circumstances; that is, on heating at a rate of 10 °C/min and under isothermal conditions at various temperatures. The deprotection resulted in a significant decrease in the transmittance of visible light due to the formation of a large number of gas bubbles, that is, foaming, in the polymer films when a heating temperature was close to the glass transition temperature of the used polymer. The potential of BOC‐containing polymers was also evaluated as the heat‐responsive adhesive polymers for dismantlable adhesion. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46252. [ABSTRACT FROM AUTHOR]

ABSTRACT Dialkyl fumarates as 1,2-disubstituted ethylenes exhibit unique features of radical polymerization kinetics due to their significant steric hindrance in propagation and termination processes and provide polymers with a rigid chain structure different from conventional vinyl polymers. In this study, we carried out reversible addition-fragmentation chain transfer polymerization of diisopropyl fumarate (DiPF) in bulk at 80 °C using various dithiobenzoates with different leaving R groups as chain transfer agents to reveal their performance for control of molecular weight, molecular weight distribution, and chain end functionality of the resulting poly(DiPF) (PDiPF). 2-(Ethoxycarbonyl)-2-propyl dithiobenzoate ( DB1) and 2,4,4-trimethyl-2-pentyl dithiobenzoate ( DB2) underwent fragmentation and reinitiation at a moderate rate and consequently led to the formation of PDiPF with well-controlled chain structures. It was confirmed that molecular weight of PDiPF produced by controlled polymerization with DB1 and DB2 agreed with theoretical one and molecular weight distribution was narrow. Dithiobenzoate and R fragments were introduced into the polymer chain ends with high functionality as 95% by the use of DB1. In contrast, polymerizations using 1-(ethoxycarbonyl)benzyl dithiobenzoate ( DB3), 1-phenylethyl dithiobenzoate ( DB4), and 2-phenyl-2-propyl dithiobenzoate ( DB5) resulted in poor control of molecular weight, molecular weight distribution, and chain end structures of PDiPF. Fragmentation and reinitiation rates of the used benzoates as chain transfer agents significantly varied depending on the R structures in an opposite fashion; that is, introduction of bulky and conjugating substituents accelerated fragmentation, but it retarded initiation of DiPF polymerization. It was revealed that balance of fragmentation and reinitiation was important for controlled polymerization of DiPF. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3266-3275 [ABSTRACT FROM AUTHOR]

Radical copolymerization of N-substituted maleimides (RMIs) and maleic anhydride (MAn) in combination with 2,4-dimethyl-1,3-pentadiene (DMPD) and 1,3-pentadiene (PD) provides alternating copolymers with excellent thermal stability. Onset temperatures of decomposition are 280-331 and 336-371 °C for the copolymers with DMPD and PD, respectively. Glass transition temperatures of RMI copolymers are in a wide range of 54-138 °C depending on the bulkiness of N-substituents. MAn copolymers are transformed to the corresponding RMI copolymers by postpolymerization reactions, which consist of quantitative addition of an alkylamine to an anhydride moiety of MAn copolymers and the subsequent heating. The copolymers synthesized in this study include ozone-degradable carbon-to-carbon double bonds in their main chain. Molecular weight of the copolymers rapidly decreases by ozone degradation. Surface modification of casted polymer films is also performed by exposure to ozone-containing air. [ABSTRACT FROM AUTHOR]

ABSTRACT Crosslinking and decrosslinking reactions of poly(vinyl alcohol) (PVA) and poly(vinyl acetate) (PVAc) using an alternating copolymer of maleic anhydride and 2,4-dimethyl-1,3-pentadiene (PMAD) as the polyfunctional crosslinker and subsequent ozone degradation are reported. PVA and PVAc are heated at 200 °C for 0.5 to 3 h in the presence of 5 to 30 wt % of PMAD in the solid state to obtain the corresponding crosslinked polymers. The reactions of a hydroxy group of PVA and an acetate group of PVAc with an anhydride group of PMAD slowly proceed to give insoluble polymers with a loose crosslinking structure. Almost no change in the thermal decomposition temperatures and the IR spectra is observed during the crosslinking reactions. The crosslinked PVA produces hydrogels with a high swelling ratio of 500 to 1700%, which are readily degradable during a reaction with ozone in water at 0 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44229. [ABSTRACT FROM AUTHOR]

ABSTRACT We report the thermal, optical, and mechanical properties of random copolymers produced by radical copolymerizations of diisopropyl fumarate (DiPF) with 1-adamantyl acrylate (AdA) and bornyl acrylate (BoA). The effects of a methylene spacer included in the main chain and bulky ester alkyl groups in the side chain on the copolymer properties are discussed. The produced copolymers are characterized by NMR and UV-vis spectroscopies, size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis (DMA). The copolymerization rate and the molecular weight of the copolymers increase with an increase in the acrylate content in feed during the copolymerization ( Mw = 25-110 × 103). The onset temperature of decomposition ( Td5) and the glass transition temperature ( Tg) of the copolymers also increase according to the content of the acrylate units ( Td5 = 296-329 °C and 281-322 °C, Tg = 80-133 °C and 91-106 °C for the copolymers of DiPF with AdA and BoA, respectively). Transparent and flexible copolymer films are obtained by a casting method and their optical properties such as transparency and refractive indices are investigated ( nD = 1.478-1.479). The viscoelastic data of the copolymers are collected by DMA measurements under temperature control. The storage modulus decreases at a temperature region over the Tg value of the copolymers, depending on the structure and amount of the acrylate units. The sequence structure of the copolymers is analyzed based on monomer reactivity ratios and composition in order to discuss the copolymer properties related to chain rigidity and sequence length distribution. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 288-296 [ABSTRACT FROM AUTHOR]

ABSTRACT Radical copolymerization of N-phenylmaleimide (PhMI) is carried out with various diene monomers including naturally occurring compounds and the copolymers are efficiently produced by the suppression of Diels-Alder reaction as the competitive side reaction. Diene monomers with an exomethylene moiety and a fixed s-trans diene structure, such as 3-methylenecyclopentene and 4-isopropyl-1-methyl-3-methylenecyclohexene, exhibit high copolymerization reactivity to produce a high-molecular-weight copolymer in a high yield. The copolymerization of sterically hindered noncyclic diene monomers, such as 2,4-dimethyl-1,3-pentadiene and 2,4-hexadiene, also results in the formation of a high-molecular-weight copolymer in a moderate yield. The NMR spectroscopy reveals that the obtained copolymers consist of predominant 1,4-repeating structures for the corresponding diene unit. The copolymers have excellent thermal stability, that is, an onset temperature of decomposition over 330 °C and a glass transition temperature over 130 °C. The copolymerization reactivity of these diene monomers is discussed based on the results of the DFT calculations. The efficient copolymer formation in competition with Diels-Alder addition is investigated under various conditions of the temperature, solvents, and initiators used for the copolymerization. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3616-3625. [ABSTRACT FROM AUTHOR]

ABSTRACT Living radical polymerizations of diisopropyl fumarate (DiPF) are carried out to synthesize poly(diisopropyl fumarate) (PDiPF) as a rigid poly(substituted methylene) and its block copolymers combined with a flexible polyacrylate segment. Reversible addition-fragmentation chain transfer (RAFT) polymerization is suitable to obtain a high-molecular-weight PDiPF with well-controlled molecular weight, molecular weight distribution, and chain-end structures, while organotellurium-mediated living radical polymerization (TERP) and reversible chain transfer catalyzed polymerization (RTCP) give PDiPF with controlled chain structures under limited polymerization conditions. In contrast, controlled polymerization for the production of high-molecular-weight and well-defined PDiPF is not achieved by atom transfer radical polymerization (ATRP) and nitroxide-mediated radical polymerization (NMP). The block copolymers consisting of rigid poly(substituted methylene) and flexible polyacrylate segments are synthesized by the RAFT polymerization. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2136-2147 [ABSTRACT FROM AUTHOR]

ABSTRACT Crosslinking and de-crosslinking reactions of an alternating copolymer of maleic anhydride (MAn) and 2,4-dimethyl-1,3-pentadiene (DMPD) by thermal curing with polyfunctional alcohols as the crosslinkers and subsequent ozone degradation are reported in this article. The ring-opening reaction of an anhydride group by polyfunctional alcohols produces network polymers with an ester linkage. The rate of crosslinking reaction depends on the curing conditions, i.e. the structure of the used alcohols and the curing temperature and time. The crosslinking density of the alcohol-cured copolymers is low due to a slow reaction between the anhydride and hydroxy groups, being different from the corresponding epoxy-cured copolymer with a dense network structure reported in a previous article. The insoluble resins are readily de-crosslinked and solubilized by ozone degradation. The polymer surface modification by ozone is also investigated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42763. [ABSTRACT FROM AUTHOR]

ABSTRACT Functional poly(diene sulfone)s are prepared by the radical alternating copolymerization of 1,3-diene monomers containing an ester substituent with sulfur dioxide. Methyl 3,5-hexadienoate (MH) and methyl 5,7-octadienoate (MO) with both an alkylene spacer and a terminal diene structure are suitable to produce a high-molecular-weight copolymer in a high yield, while the copolymerization of 5,7-nonadienoic acid, ethyl 2,4-pentadienoate, and ethyl 4-methyl-2,4-pentadienoate including either an alkylene spacer or a terminal diene structure lead to unsuccessful results. The 13C NMR chemical shift values of MH and MO suggest a high electron density at their reacting α-carbon for exhibiting a high copolymerization reactivity. Fluorene-containing diene monomers, 9-fluorenyl 3,5-hexadienoate (FH) and 9-fluorenyl 5,7-octadienoate (FO), are also prepared and copolymerized with sulfur dioxide. The thermal and optical properties of the poly(diene sulfone)s containing the methyl and fluorenyl ester substituents in the side chain are investigated. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1000-1009 [ABSTRACT FROM AUTHOR]

ABSTRACT We prepared the sequence-controlled block copolymers including poly(1-adamantyl acrylate) (PAdA) and poly( n-butyl acrylate) sequences as the hard and soft segments, respectively, by the organotellurium-mediated living radical polymerization. The thermal, optical, and mechanical properties of the adamantane-containing block copolymers with polar 2-hydroxyethyl acrylate (HEA) and acrylic acid (AA) repeating units were investigated. The microphase-separated structures of the block copolymers were confirmed by the differential scanning calorimetry and atomic force microscopy observations as well as dynamic mechanical measurements. The α- and β-dispersions due to the main-chain and side group molecular motions, respectively, of the hard and soft segments were observed. Their transition temperatures and activation energies increased due to the formation of intermolecular hydrogen bonding by the introduction of the HEA and AA repeating units. The effects of the hydrogen bonding on their tensile elasticity, strength, and strain were also evaluated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2899-2910 [ABSTRACT FROM AUTHOR]

K- Ar ages have been determined for 14 late Miocene to Pliocene volcanic rocks in the north of the Kanto Mountains, Japan, for tracking the location of the volcanic front through the time. These samples were collected from volcanoes located behind the trench-trench-trench ( TTT) triple junction of the Pacific, Philippine Sea, and North American plates. This junction is the site of subduction of slabs of the Pacific and the Philippine Sea plates, both of which are thought to have influenced magmatism in this region. The stratigraphy and K- Ar ages of volcanic rocks in the study area indicate that volcanism occurred between the late Miocene and the Pliocene, and ceased before the Pleistocene. Volcanism in adjacent areas of the southern NE Japan and northern Izu- Bonin arcs also occurred during the Pliocene and ceased at around 3 Ma with the westward migration of the volcanic front, as reported previously. Combining our new age data with the existing data shows that before 3 Ma the volcanic front around the TTT junction was located about 50 km east of the preset-day volcanic front. We suggest that northward subduction of the Philippine Sea Plate slab ended at ∼3 Ma as a result of collision between the northern margin of the plate with the surface of the Pacific Plate slab. This collision may have caused a change in the subduction vector of the Philippine Sea Plate from the original north-directed subduction to the present-day northwest-directed subduction. This indicates that the post ∼3 Ma westward migration of the volcanic front was a result of this change in plate motion. [ABSTRACT FROM AUTHOR]

The radical copolymerization of N-substituted maleimides containing polymethylene and poly(ethylene oxide) side chains as the N-substituent groups with isobutene, styrene, and α-methylstyrene as the electron-donating monomers is carried out in order to investigate the structure and thermal properties of the resulting comb-like copolymers. The obtained copolymers show excellent thermal stability and their glass transition temperatures vary depending on the chain length of the introduced N-substituents. The main- and side-chain motions of the copolymers are investigated by dynamic mechanical analysis at various frequencies over the temperature range of −150 to 100 °C. [ABSTRACT FROM AUTHOR]

The radical alternating copolymerization of N-substituted maleimides (RMIs) with N-methyl, n-butyl, and 2-ethylhexyl groups and styrene derivatives with various α-substituents (RSs) is carried out. The yield and the molecular weight of the obtained copolymers significantly decrease with an increase in the size of the α-substituent of RSs, but are independent of the N-substituents. The glass-transition temperature of the copolymers increases on the introduction of the large substituents into the RS repeating units. The high-molecular-weight poly(RMI- alt-RS)s are soluble in organic solvents and provide flexible and transparent films with excellent transparency by casting the solutions. [ABSTRACT FROM AUTHOR]

Copolymers with a 2:1 regulated sequence of N-phenylmaleimide with β-pinene units (AAB-type repeating units) are produced during radical copolymerization. The monomer reactivity ratios are determined using the penultimate unit model, and it is demonstrated that they vary depending on the solvent used (tetrahydrofuran, 1,2-dichloroethane, 2,2,2-trifluoroethanol, and perfluoro- tert-butanol) and the copolymerization temperature (0-100 °C). The interaction of the PhMI repeating units with solvents lead to the production of the 2:1 controlled sequence and a significant change in the relative reactivity of the PhMI radicals by polar and steric effects. [ABSTRACT FROM AUTHOR]

A buried, old volcanic body (pre-Komitake Volcano) was discovered during drilling into the northeastern flank of Mount Fuji. The pre-Komitake Volcano is characterized by hornblende-bearing andesite and dacite, in contrast to the porphyritic basaltic rocks of Komitake Volcano and to the olivine-bearing basaltic rocks of Fuji Volcano. K-Ar age determinations and geological analysis of drilling cores suggest that the pre-Komitake Volcano began with effusion of basaltic lava flows around 260 ka and ended with explosive eruptions of basaltic andesite and dacite magma around 160 ka. After deposition of a thin soil layer on the pre-Komitake volcanic rocks, successive effusions of lava flows occurred at Komitake Volcano until 100 ka. Explosive eruptions of Fuji Volcano followed shortly after the activity of Komitake. The long-term eruption rate of about 3 km3/ka or more for Fuji Volcano is much higher than that estimated for pre-Komitake and Komitake. The chemical variation within Fuji Volcano, represented by an increase in incompatible elements at nearly constant SiO2, differs from that within pre-Komitake and other volcanoes in the northern Izu-Bonin arc, where incompatible elements increase with increasing SiO2. These changes in the volcanism in Mount Fuji may have occurred due to a change in regional tectonics around 150 ka, although this remains unproven. [ABSTRACT FROM AUTHOR]